This section introduces aspects that may facilitate a better understanding of the disclosure. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.
Fifth generation (5G) networks such as NR, New Radio are supposed to provide diverse applications or services by using the same physical infrastructure. FIG. 1 schematically shows an example 5G network 100. As illustrated in FIG. 1, the network 100 may support multiple types of mobile network services, e.g., services 120-1, 120-2, 120-3, via a common Radio Access Network (RAN) 110. Those different types of mobile network services 120-1, 120-2, 120-3 are independent one another in a logic level but may be implemented in the same physical infrastructure. Depending on different Quality of Services (QoS) requirements, these mobile network services may be classified into three main types: Ultra-Reliable and Low Latency Communication (URLLC) 120-1, enhanced Mobile BroadBand (eMBB) 120-2, massive Machine Type Communication (mMTC) 120-3.
URLLC 120-1, e.g., being used in automatic drive/automatic control, has strict QoS requirements, especially in terms of latency and reliability. However, such URLLC services usually also has relatively low data rate and possible sparse data transmission.
mMTC 120-2, e.g., being used in intelligent agriculture, typically supports high connection density and requires long battery lifetime but does not require low delay or high data rate, often combined with small infrequent packets;
eMBB 120-3, e.g., being used in HD video service, requires high data rate. Delay can be strict but typically less strict than in URLLC.
In order to fulfill the delay requirement of different services, it is agreed in the RAN 1 (such as RAN 110 in FIG. 1) to introduce mixed numerologies in one carrier so that the services mentioned above can be served over one carrier.
A network, such as the fourth generation (4G) network, relies on the retransmission functionalities in multiple layers to avoid packet loss in the whole transmission path including the transport network and RAN network. Some example retransmission functionalities include Automatic Repeat Request (ARQ) in Transmission Control Protocol (TCP) layer, Packet Data Convergence Protocol (PDCP) and Radio Link Control (RLC) and Hybrid Automatic Repeat Request (HARQ) in Media Access Control (MAC) layer. For different services, there are different configurations of the mentioned layers according to the QoS requirement. For eMBB, the data is not so delay sensitive but the data rate should be as high as possible and the packet loss should be avoided. Hence the data retransmission of all layers shall be applied to avoid the packet loss. For real time video traffic, the TCP retransmission may not be applicable due to the delay budget and the data retransmission robustness relies on the RAN retransmission functionality such as RLC and MAC. For URLLC, the retransmission of TCP, PDCP and RLC may not be applicable due to URLLC's extremely small delay budget and therefore, the robustness of the data transmission mainly relies on the enhancement of the initial transmission and HARQ retransmissions.